package day07;

import java.util.Random;
/**
 * 需求：生成几位的验证码（大写字母、小写字母、数字）
 *
 */
public class VerificationCode {
    public static void main(String[] args) {
        String code = generateVeriCode(10);
        System.out.println("验证码--"+code);
    }
    //生成验证码
    public static String generateVeriCode(int len){
        String code = "";
        char[] chs = {'a','b','c','d','e','f','g','h','i',
                      'j','k','l','m','n','o','p','q','r',
                      's', 't','u','v','w','x','y','z','A',
                      'B','C','D', 'E','F','G','H','I','J',
                      'K','L','M','N','O','P','Q', 'R','S',
                      'T','U','V','W','X','Y','Z','0','1',
                      '2','3','4','5','6','7','8','9','许'};
        Random rand = new Random();
        for(int i=1;i<=len;i++){
            //int index = (int)(Math.random()*chs.length);
            int index = rand.nextInt(chs.length);//随机下标（0到61的）
            code += chs[index];//获取随机字符并拼接到code中
         /*
         i=1   index=0   code="a"
         i=2   index=61  code="a9"
         i=3   index=25  code="a9z"
         i=4   index=28  code=""
          */

        }
        return code;
    }
}